Bar-code readers are used extensively in the retail grocery industry at checkout stations to identify tagged items affixed with bar-code tags. An item is identified by means of its bar-code using a data base stored in a host computer. Typically, a description of the item and its price are printed on a grocery receipt and an ongoing price total is kept as additional items are scanned. The use of bar-code readers has generally been well received by the public, due in part, to the reliability and reduced time spent in the checkout line. However, a reliable system is needed to identify items for which it is undesirable to attach bar-code labels, for example, fresh produce, such as fruits and vegetables.
Optical characterization of fresh produce has been explored to some extent in the prior art. Some general considerations involved in the optical identification of these products are discussed in a number of publications, including for example, "Postharvest Handling: A Systems Approach", by R. L. Shewfelt and S. E. Prussia (Academic Press. New York). An example of a particular application of produce recognition is a study by L. Bochereau et al. (J. Agric. Eng. Res. (1992) Vol. 51, 207-216) showing that near infrared spectra can be used to determine the quality of golden delicious apples, provided that a careful neural-network analysis is performed in the wavelength range from 1,000 to 1,500 nm.
A number of devices are disclosed in the prior art for use in characterizing products using their optical properties. For example, Japanese patent number 03-160344 to Kenichi Yoneda and assigned to Mitsubishi Heavy Industries, Ltd. discloses a device intended to measure the ingredients of fruits. The device shines near-infrared light onto a piece of fruit, and collects the reflected light with an optical fiber. The light is dispersed with a grating and directed into an array of photo detectors. The electronic signal produced is then normalized to a reference signal and the resulting spectrum is then used to characterize the sweetness of the fruit, using the near-infrared region of the spectrum only.
Another device utilizing color-vision in conjunction with measurements of other properties is described in U.S. Pat. No. 4,884,696 to Pelag for an automatic inspection apparatus. The device utilizes-color vision reflectance and adds to it a color-vision transmission spectra. This color-vision, colorimetry or three-color method determines the effective color using light from three narrow spectral regions and is widely used. The device also includes mechanical probes to measure hardness and electrical probes for measuring dc conductivity.
It is our understanding that although the prior art presents a variety of optical identification techniques, users of the above-described methodologies have experienced some difficulty in regard to making reliable identifications of products, as well as dissatisfaction with respect to the time in which it takes to make an identification. Moreover, the cost of implementing such systems on a wide-scale has also proved to be prohibitive.
It is therefore an object of the present invention to provide an optical identification system for recognizing fresh produce and other products, wherein the system makes reliable identifications and is cost efficient. It is further an object of the present invention to provide an optical identification system which is easily integratable with bar code scanners used in the supermarket industry.